1. Field of the Invention
The present invention relates to a vehicle door mirror and, more particularly, to a vehicle door mirror that is capable of restraining wind noise, especially whistling sounds, produced by an airflow passing through a gap between a mirror base and a mirror housing when the vehicle is running.
2. Description of the Related Art
A vehicle door mirror is generally configured so that a mirror base is mounted to a vehicle door, a rotation shaft is installed in a standing manner on the upward surface of the mirror base, and a mirror housing is rotatably supported on the rotation shaft, and is also configured so that the mirror housing can be displaced selectively to a storage position (not-in-use position) and a restoration position (in-use position) by being turned around the rotation shaft manually or electrically. In the vehicle door mirror having the above-described configuration, since the upward surface of the mirror base faces to the downward surface of the mirror housing which faces to the upward surface of the mirror base via a gap, there arises a problem in that uncomfortable whistling sounds are produced by an airflow passing through the gap when the vehicle is running. The whistling sounds are produced because the airflow passing through the gap is a straight flow.
A conventional art for restraining whistling sounds produced by the airflow passing through the gap between the mirror base and the mirror housing when the vehicle is running is described in Japanese Patent No. 3508088. In the art described in Japanese Patent No. 3508088, a large number of dimples (depressions) are formed in the surface of the mirror housing or the mirror base facing to the gap, whereby the airflow passing through the gap is disturbed by the dimples to become turbulent to restrain the whistling sounds.
According to the art described in Japanese Patent No. 3508088, the whistling sound restraining effect is easily affected by the variations in gap size. Even if the gap increases slightly, the airflow passing through the gap becomes a straight flow, and thereby the whistling sound restraining effect cannot be achieved.